1. Field of the Invention
The present invention relates to image compression using wavelet transforms, spatial database, metadata and geographical information system (GIS)
2. Description of the Prior Art
GIS software has a variety of functionality including panning and zooming of geographic maps, querying information from a database, and performing geographic analysis. Such functionality typically requires a highend computer. Thus, GIS is expensive for organizations with multiple offices since all offices would require both computer and copy of the GIS software. Furthermore, all offices contribute to the maintenance of the central database requiring high network bandwidth. The present invention can reduce this cost and offer partial GIS functionality. A single server is maintained in a central location while remote sites access the server over the World Wide Web. Complex software is not required on the client, only a Java enabled web browser. Thus, typical PC can be used at the remote sites. However, the major problem of transferring the large amount of data in a reasonable time remains to be addressed. This problem is minimized by utilizing two different approaches offering multiple resolutions of the image and using data compression. In many cases, GIS users want to determine different area or same area in different time. This invention helps this situation by offering the mosaic feature that user can combine different maps to together to form a larger image for comparison or analysis purpose.
The present invention offers a choice of multiresolution images to the user; therefore, high-resolution images are transferred over the internet only when the user requires such detailed images. The multiple resolution images are created using a wavelet transformation. A further benefit of the wavelet transformation is that it reduces the typically high entropy of an image, thus, transforming the image to format highly compressable using typical data compression algorithms. The wavelet transformation will generally be more efficient in entropy reduction than other data transformations, since the localized representation of the data utilized two domains (time and scale) whereas other transformations utilize only one domain. Once the data is transformed into a wavelet data stream and compressed, the amount of data being transferred over World Wide Web is minimized.
This system comprises of a server process, a client process, a spatial database and a relational database. It presents the idea of geographical information access over the World Wide Web network using compression technology and data filtering—in the form of queries and metadata—for efficient use of network bandwidth. In addition, the user can access or change information using the tools provided inside the client application.
General GIS features and capabilities can be provided with the client application without loading the client machine. Commands are passed to the server, which accesses the spatial and relational databases to process the commands. The server retrieves the data and the result is sent to the client application. Therefore, users can access and use the features of the GIS server and its corresponding databases using a standard PC.